effects of currents to net-cage systems and good agreement was found between the
numerical results and prior experimental findings (Huang et al. 2006).
Experimental studies most often provide the basis for numerical modelling
attempts, help calibrating numerical models and verify achieved simulation results.
Experimental research offers down-scaled, controllable and repeatable conditions
for reliable analysis which becomes increasingly important as study sites move
from more sheltered near-coast regions to high-energetic offshore sites. The effects
of current-only conditions on down-weighed flexible circular nets were investigated
in greater detail experimentally by Lader and Enerhaug (2005). They emphasized
that forces on and deformations of flexible nets are mutually highly dependent on
each other. This in particular applies to aquaculture sites residing in the open ocean
with harsh environments. The suitability of a modified gravity-type fish cage was
similarly investigated by experimental and numerical means under exposed environmental conditions with regular waves (DeCew et al. 2005). These controlled
wave conditions allowed for the derivation of motion response in heave, surge and
pitch as well as load response in the anchor and bridle lines. The findings were then
extended to the irregular regime by the application a stochastic approach. Based on
a combination of numerical and experimental approaches Huang et al. (2008)
conjectures aquaculture activities should not be situated waters with current
velocities above 1 m/s unless volume-reducing effects can be safely restricted by
technological means. At the same time it is recommended to carefully consider the
combined effects of currents and obliged waves before facilities are installed at new
sites.
Although the tendency to aquaculture site located further off the shore is well
traceable in literature there are generally much fewer sources which explicitly focus
on the combination of different aquaculture applications at one location or even
inclusion of non-aquaculture elements such as support structures from other
industries in the open ocean. Buck and Buchholz (2005) discussed the co-use of
existing or planned offshore structures for the growth of Laminaria saccharina by
comparing drag forces measured in a current flume with those resulting from
conditions in the North Sea. The authors also reported on the development of a
devices to culture macroalgae in a range of offshore conditions (Buck and Buchholz
2004). Based on the analysis of the current development inside the continental shelf
around the world Lacroix and Pioch (2011) plead innovative efforts to move
towards eco-engineered structures such as artificial fishing reefs or the incorporation of secondary purposes within wind farms. The mutual benefits of wave energy
converter foundations as artificial reefs were examined for a building site about
100 km north of Gothenburg at the Swedish coast (Langhamer and Wilhelmsson
2009). It was found that basically the amount of fish and crab on the ground of the
foundations was considerably increase whereas the abundance of fish in the water
column above was not substantially altered. Another example of the multi-use idea
is the development of artificial reefs which oftentimes serve not only the purpose to
provide valuable habitat to marine species but also serve as one additional form of
coastal protection (Liu and Su 2013).
74
N. Goseberg et al.
numerical results and prior experimental findings (Huang et al. 2006).
Experimental studies most often provide the basis for numerical modelling
attempts, help calibrating numerical models and verify achieved simulation results.
Experimental research offers down-scaled, controllable and repeatable conditions
for reliable analysis which becomes increasingly important as study sites move
from more sheltered near-coast regions to high-energetic offshore sites. The effects
of current-only conditions on down-weighed flexible circular nets were investigated
in greater detail experimentally by Lader and Enerhaug (2005). They emphasized
that forces on and deformations of flexible nets are mutually highly dependent on
each other. This in particular applies to aquaculture sites residing in the open ocean
with harsh environments. The suitability of a modified gravity-type fish cage was
similarly investigated by experimental and numerical means under exposed environmental conditions with regular waves (DeCew et al. 2005). These controlled
wave conditions allowed for the derivation of motion response in heave, surge and
pitch as well as load response in the anchor and bridle lines. The findings were then
extended to the irregular regime by the application a stochastic approach. Based on
a combination of numerical and experimental approaches Huang et al. (2008)
conjectures aquaculture activities should not be situated waters with current
velocities above 1 m/s unless volume-reducing effects can be safely restricted by
technological means. At the same time it is recommended to carefully consider the
combined effects of currents and obliged waves before facilities are installed at new
sites.
Although the tendency to aquaculture site located further off the shore is well
traceable in literature there are generally much fewer sources which explicitly focus
on the combination of different aquaculture applications at one location or even
inclusion of non-aquaculture elements such as support structures from other
industries in the open ocean. Buck and Buchholz (2005) discussed the co-use of
existing or planned offshore structures for the growth of Laminaria saccharina by
comparing drag forces measured in a current flume with those resulting from
conditions in the North Sea. The authors also reported on the development of a
devices to culture macroalgae in a range of offshore conditions (Buck and Buchholz
2004). Based on the analysis of the current development inside the continental shelf
around the world Lacroix and Pioch (2011) plead innovative efforts to move
towards eco-engineered structures such as artificial fishing reefs or the incorporation of secondary purposes within wind farms. The mutual benefits of wave energy
converter foundations as artificial reefs were examined for a building site about
100 km north of Gothenburg at the Swedish coast (Langhamer and Wilhelmsson
2009). It was found that basically the amount of fish and crab on the ground of the
foundations was considerably increase whereas the abundance of fish in the water
column above was not substantially altered. Another example of the multi-use idea
is the development of artificial reefs which oftentimes serve not only the purpose to
provide valuable habitat to marine species but also serve as one additional form of
coastal protection (Liu and Su 2013).
74
N. Goseberg et al.